Optical damage of optical elements is a problem presented by the operation of high power laser systems. Reflective optics are often used to direct laser beams by changing the direction of propagation (e.g., using mirrors) or to control the divergence of the laser beam (e.g., using lenses to focus the laser beam to a spot). Both refractive optical elements and reflective optical elements are widely used in laser systems.
Typically, laser systems utilize multi-layer dielectric mirrors that can be damaged during operation. Damage to dielectric mirrors can arise as a result of preexisting defects such as impurities, structural or lattice imperfections, or contamination. These preexisting defects can be embedded in the surface of the optic or can be present in the bulk of the material and can result from the manufacturing process or as a result of handling the optic. Damage can also arise as defects generated during the operation of the system or due to local field enhancements in the laser beam.
Despite progress made in the reliability of high power laser systems, there is a need in the art for improved methods and systems related to high power reflective optical elements.